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5HT3 Antagonists

Other names: Palonosetron (Aloxi®), Ondansetron (Zofran®), Dolasetron (Anzemet®), Granisetron (Kytril®,Sancuso®)

About This Drug 

5-HT3 Receptor Antagonists are medications that are used before and after chemotherapy to prevent or treat nausea or vomiting. These medications may be given in the vein (IV), as an oral tablet by mouth, as an oral disintegrating tablet, or as a patch.

Possible Side Effects 

  • Constipation (not being able to move bowels)
  • Diarrhea (loose bowel movements)
  • Headache
  • Feeling dizzy

Note: Not all possible side effects are included above.

Warnings and Precautions  

  • Abnormal heart beat and/or abnormal EKG
  • Allergic reactions, including anaphylaxis are rare but may happen in some patients. Signs of allergic reaction to this drug may be swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way. If this happens, do not take another dose of this drug. You should get urgent medical treatment.

How to Take Your Medication

  • Please refer to the package insert for the specific medicine you are taking for information on how to take your medicine.

Treating Side Effects 

  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack of water in the body from losing too much fluid).
  • If you get diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • If you are not able to move your bowels, check with your doctor or nurse before you use enemas, laxatives, or suppositories.
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea and/or constipation.
  • Keeping your pain under control is important to your well-being. Please tell your doctor or nurse if you are experiencing a headache.
  • If you are dizzy, get up slowly after sitting or lying.

Food and Drug Interactions 

  • There are no known interactions of 5HT3 with food.
  • These drug may interact with other medicines. Tell your doctor and pharmacist about all the medicines and dietary supplements (vitamins, minerals, herbs and others) that you are taking at this time. The safety and use of dietary supplements and alternative diets are often not known. Using these might affect your cancer or interfere with your treatment. Until more is known, you should not use dietary supplements or alternative diets without your cancer doctor's help.

When to Call the Doctor 

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Headache that does not go away
  • Feeling dizzy or lightheaded
  • Feeling that your heart is beating in a fast or not normal way (palpitations)
  • Nausea that stops you from eating or drinking and/or is not relieved by prescribed medicines
  • Throwing up more than 3 times a day
  • No bowel movement in 3 days or when you feel uncomfortable
  • Diarrhea, 4 times in one day or diarrhea with lack of strength or a feeling of being dizzy
  • Signs of allergic reaction: swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way

Reproduction Warnings 

  • Pregnancy warning: These drugs are not expected to harm an unborn child. Talk to your doctor about the use of this drug if you are pregnant or plan to become pregnant.
  • Breastfeeding warning: It is not known if these drugs passes into breast milk. For this reason, women should talk to their doctor about the risks and benefits of breastfeeding during treatment with these drugs because this drug may enter the breast milk and cause harm to a breast-feeding baby.
  • Fertility warning: These drugs are not expected to affect your ability to have children in the future. Human fertility studies have not been done with this drug.

Revised April 2019